The present invention relates generally to optical systems for guiding a laser beam. More particularly, the present invention relates to a constant tool center point optical system for guiding a laser beam in a cutting device.
Laser cutting devices are well known. These devices typically include a relatively large energy source for producing an energy beam. The size of the energy source makes it preferable to fixedly mount the energy source. Accordingly, in the early designs for laser cutting devices, the energy source was mounted at an angle that was desired to be cut into a workpiece. When a different angle was desired, the energy source was turned off and then repositioned. Thus, it was difficult and time consuming to cut numerous angles in a single workpiece.
To avoid these difficulties, mirrors were positioned between the energy source and the workpiece. Adjustment of the mirrors allowed a variety of angles to be cut into the workpiece. However, complicated control circuitry was required to direct the position of the mirrors to enable the laser beam to cut at different angles.
Constant tool center point cutting devices were then developed to assist in forming angled cuts in a workpiece. In a constant tool center point cutting device, the cutting point of the devices remains constant and the workpiece is cut by moving the workpiece to the cutting point of the device. A prior art constant tool center point cutting device, such as is illustrated at 10 in FIG. 1, allows a directing mechanism 12 of the cutting device 10 to be rotated about an axis 14. As the directing mechanism 12 is rotated, an energy beam 16 is continually focused to a constant point 18. Because the focal point of the energy beam 16 is always at the constant point 18, the cutting device 10 does not require a use of an offset handling controller to direct the energy beam 16 as the directing mechanism 12 is rotated.
Another prior art constant tool center point cutting device is illustrated at 40 in FIG. 2. A directing mechanism 41 of the cutting device 40 uses four mirrors 42, 44, 46, and 48 to direct an energy beam 50 toward a focal point 52. In addition to having a constant tool center point, the cutting device 40 allows the cutting angle 54 to be adjusted by rotating a first section 56 of the directing mechanism 41 about an axis 58. Beam alignment in the four mirror design is complicated because there is five axes of rotation that must be aligned.